bookland

The word bookland does not appear in Domesday Book (though there is one occurrence in the Exeter Domesdaysatellitetext); but its characteristics are believed to have shaped many Anglo-Saxon tenures.

Bookland was land held by book, or charter, in perpetuity. Originally
created to endow the Church after the coming of Christianity, royal
grants of bookland were by the eighth century being made to laymen and
were much sought after due to the royal rights they conferred and the
greater freedom of alienation they allowed. By the eleventh century it
is likely that most land was regarded as bookland unless there were
clear evidence to the contrary. One distinctive survival, however, was sokeland, mostly located in the Danelawcounties. On sokeland, the lord had to the right to those royal duesand
renders alienated by a royal book at some time in the past; but he did
not own the soil, and his tenants were free to dispose of their
property. If they did so, however, the purchaser incurred the obligation
to pay the dues with which the soke was encumbered.

For more detail, see Richard P. Abels, Lordship and military obligation in Anglo-Saxon England (1988); Susan Reynolds, 'Bookland, folkland and fiefs', Anglo-Norman studies, vol. 14 (1992), pages 211-27; and David Roffe, Domesday: the Inquest and the Book (2000).